The present invention relates to thermostatic valve arrangement for a coolant control of an internal-combustion engine, having a thermostatic working element which is assigned to the coolant flow and the working piston of which is supported on an abutment. The abutment is adjustable by an adjusting member which is arranged outside the coolant flow and is held in a receiving device that is constructed in one piece with a valve housing.
German Patent Document DE-GM 90 15 766.4 shows a thermostatic valve arrangement in which the adjusting member is fitted into the receiving device of the valve housing made of an aluminum die casting and is held by means of a flanged construction. The piston of the adjusting member, which is constructed as a thermostatic working element, penetrates the valve housing. It is surrounded by a sealing ring.
An object of the present invention is to develop a thermostatic valve arrangement of the earlier described type in such a manner that the adjusting member can be detached from the valve housing and that this detachment can be carried out without allowing coolant to subsequently flow out via the receiving device.
This and other objects are achieved by the present invention which provides a valve housing that is made of a plastic material, with the adjusting member being detachably held in the receiving device by means of holding elements. Between the adjusting member and the working piston, transmitting devices are arranged which have the purpose of transmitting pressure forces and form a sealing device which seals off the valve housing in the direction of the receiving device.
The manufacturing of the valve housing made of a plastic material is advantageously simple and also has the advantage of a thermal separation from the adjusting member so that the temperature of the coolant does not interfere with the adjusting member.
Another advantage is that transmitting devices are arranged between the adjusting member and the working piston so that the adjusting member does not project into the coolant flow. In addition, the adjusting member is removable so that it can be detached from the housing for a check-up or an exchange. Since the sealing in the area of the transmitting devices takes place in such a manner that the adjusting member does not at all extend into the coolant flow, the coolant flow remains sealed off toward the outside even when the adjusting member is removed. The adjusting member can therefore be demounted and exchanged without the risk that coolant may flow out.
In an embodiment of the invention, the transmitting element is guided by a piston-type projection (or rod) in a bore leading to the receiving device and is surrounded by a sealing device. Thus, a reliable sealing is ensured in a simple manner.
In certain embodiments of the invention, the adjusting member is another thermostatic working element which is arranged in the receiving device in such a manner that a working piston is arranged coaxially with respect to the working piston of the first working element. Between the two working pistons, a transmitting element made of a heat-insulating material is arranged. As a result, it is possible to design the thermostatic working element serving as the adjusting element in such a manner that it responds to the ambient temperature and can therefore cause a control of the coolant temperature that is superimposed with this value. Since the valve housing is made of a plastic material and since the transmitting element also consists of a heat-insulating material, such as plastic, no direct heat transmittance takes place from the coolant to the adjusting member so that this adjusting member can in fact respond to the ambient temperature.
In certain embodiments of the invention, the valve housing and/or the receiving device are provided with devices for reducing a heat transmittance from the valve housing to the adjusting member. This results in a further improved thermal separation between the coolant and the adjusting member.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.